On my PC it's considerably less stable now, most crashes seem to be linked to the rendering system, which I understand has undergone some changes in the area of shadow generation.
However despite a few other minor bugs I too am loving the changes to the game mechanics, think there is still some balancing to do as well as fixing stability issues until the patch is released though.
And to the OP frankly you new this time you where down loading a beta, you can't complain about the stability of a beta that's kind of part of what they are testing. The fact is major engine revisions like multithreading AI and rewritting rendering code is bound to lead to some stability issues that need ressolving hence the Beta.